C0SM0TR1CHE POTATORIA. 167 



2. — Ova (from Tenby) : Colour of a delicate pale grey-green, with trans- 

 lucent dark spot at micropyle, and another on upper and lower sides, which are often 

 depressed centrally; length i-8mm. — i-cjmm., width i-6mm. There is no trace whatever 

 of the usual longitudinal bands in the greater number of eggs in this batch, one or two 

 eggs onlv showing indistinct traces thereof. The eggs are considerably less in bulk 

 than are those forming a batch sent by Edelsten, and 6btained about the same 

 time in the Xorfolk Broads; many of these latter measured 2 , 3mm. in length, and 

 i '8mm. in width (Bacot, August 12th, 1900). 



Buckler describes the egg as : 



Rather large, roundish-ovate, some being of a rounder shape than others, 

 having a small, rather shallow, circular depression above, and a deeper one beneath, 

 the surface smooth, the colour opaque shining white, like porcelain ; the depressions 

 above and below are light greyish-green, and also the zones, which, at some distance, 

 surround each depression, and a smallish depressed round spot of the same colour 

 midway between the two zones (Larvae, Sec, iii., p. 60). 



Habits of larva. — The larvae leave the egg in August, and im- 

 mediately eat about half the eggshell (Ransom), they are very active and 

 strong when hatched, and do not appear to suffer at all by wandering 

 about in search of food for a day or two (Edwards) ; they hybernate 

 small (4th instar) commencing in October or early November, feed 

 up rapidly the following April to June when they usually pupate. As an 

 exception to this general rule Syme notes {"Scot. Nat." ii., p. 176) that 

 the larvae hybernate fullfed in Bute, like those of M. rubi, but Dalglish 

 says that in the Clyde district they hybernate when about halfgrown, 

 as in the south. Chitty notes finding a fullgrown larva on August 1 3th, 

 1 891, at Deal, which spun up directly after capture, the imago emerging 

 the second week in September, evidently a simple case of delay for 

 a month, in the larval stage. Decie notes a larva taken May 

 21st, 1894, at Bockleton when it appeared to be halfgrown, but 

 instead of spinning-up at the usual time, it fed up, scarcely increasing 

 at all in size throughout the summer and autumn and winter and was 

 quite healthy in January, 1885, whilst Colthrup records a larva from 

 Chichester that hybernated small in the winter of 1898-9, fed on 

 slowly through the summer and autumn of 1899, hybernated 

 again through the winter of 1899 — 1900, but died at the end 

 of April, j 900, owing to food not being supplied when it became 

 active after hybernation. Crass says that the larvae are sluggish but 

 fond of sun, he noticed also that they rubbed their heads in the drops of 

 water with which their food had been sprinkled ; and Bostock says that 

 they were especially abundant on a warm rainy day in Derbyshire ; 

 Bensel and Belling note (Berl. Ent. Zeits., xliv., p. 14) that larvae are 

 easily reared if the larvae and their food are copiously sprinkled with 

 water which they love to drink, a habit quite usual with them in nature. 

 Curtis writes : "The name of ' drinker' caterpillar was given to this 

 insect more than a century back by Goedart, from his imagining that 

 it is subject to thirst and that when it drinks it takes breath, 

 lifting the head up to swallow the water more easily." This 

 note appears to be sceptical in tone, but Hoffmann and 

 Keller write: "Although the name indicates it, yet it is little known 

 that the larva drinks water with great greediness." Hall notes 

 (B?it. Nat., i., p. 76) that he finds most larvae on warm damp 

 evenings, at Sheffield, when the herbage is saturated with moisture 

 the larvae revelling in it, and eagerly drinking the drops of water 

 on the grass. He further suggests that success in rearing the species 

 largely depends on their having sufficient water sprinkled over 



